A method for evaluating data from a reciprocating downhole pump includes the steps of acquiring downhole position and load data, providing the position and load data to a processing unit, normalizing the position and load data, converting the position and load data to a calculated polar coordinate data set, evaluating the calculated polar coordinate data set to determine a condition or occurrence at the reciprocating pump, and outputting calculated key parameters for controlling and optimizing the reciprocating pump and beam pumping unit. The method further comprises a step of creating a library of reference data sets, comparing the calculated polar data set against the library of ideal and reference data sets, identifying one or more reference data sets that match one or more portions of the calculated polar data set, and outputting the probability of one or more of the known conditions within the calculated polar data set.